Journal: Nature Communications
Article Title: EP300 deficiency leads to chronic replication stress mediated by defective replication fork protection
doi: 10.1038/s41467-025-67171-z
Figure Lengend Snippet: A Schematic model depicting replication fork stalling, fork protection, and nucleolytic degradation, (Created in BioRender. Madireddy, A. (2025), is licensed under CC BY 4.0, https://BioRender.com/xtm4wme ). B DNA fiber analysis of 50uM hydroxyurea (HU) (60 min) treated EP300WT (NA1, NA4), EP300Mut (NA2, NA3) and EP300WT NA-ATLL (NA1, NA4) cells treated with negative control (S, S) stereoisomer or with JQAD1 (500 nM for 48 h) treatment to assess replication fork stalling. The fork rate (CldU/IdU ratio) is indicated. N = 3. C DNA fiber analysis measuring nucleolytic degradation after 4 mM HU treatment in EP300WT, EP300Mut NA-ATLL cells. The fork rate (CldU/IdU ratio) is indicated, N = 3. D Analysis of the number of single-stranded gaps (ssDNA)/Iododeoxyuridine (IdU) foci (green) per cell nuclei (DAPI, blue) in EP300WT (NA4) and EP300Mut (NA2, NA3) cells exposed to 2 mM HU (4 h), and EP300WT (NA4) cells treated with JQAD1 (500 nM). ssDNA gaps are measured by IdU incorporation under non-denaturing conditions. Representative images are shown on the right, N = 3. E Analysis of number of pRPA Ser4/8 foci (red) per cell nuclei (DAPI, blue) in EP300WT (NA4) and EP300Mut (NA2, NA3) cells exposed to 2 mM HU (4 h), and EP300WT (NA4) cells treated with 500 nM JQAD1. Representative images are shown on the right, N = 3. F Protein expression of phospho-RPA Ser4/8 in the presence or absence of EP300, presented as a fold change quantified from the immunoblot in Supp. Fig. S . G Analysis of the number of single-stranded gaps/breaks (ssDNA)/Iododeoxyuridine (IdU) foci per cell nucleus (DAPI, blue) in EP300WT (NA4) and EP300Mut (NA3) cells exposed to 2 mM HU (4 h), in the presence or absence of 50uM Mirin (4 h) (Mre11 nuclease inhibitor), N = 3. H Analysis of the number of single-stranded gaps/breaks (ssDNA)/ Iododeoxyuridine (IdU) foci per cell nucleus (DAPI, blue) in EP300WT (NA4) and EP300Mut (NA3) cells exposed to 2 mM HU (4 h), in the presence or absence of 20uM C5 (24 h) (DNA2 nuclease inhibitor), N = 3. For all experiments, data are presented as mean values +/− SD. P -values were determined by a two-tailed Student T-test. P -values are indicated as follows: * <0.03, ** <0.0021, *** <0.0002, **** <0.0001. Scale bar 10 μm. N represents three experimental replicates from independent cultures of cells. Source data are provided as a Source Data file.
Article Snippet: Exponentially growing cells were labelled with 50 uM IdU for 48 hours before treatment with MRE11 inhibitor- Mirin, DNA2 inhibitor- C5 (HY-128729, MedChem express) and 2 mM hydroxyurea in the last 4 h prior to collection.
Techniques: Negative Control, Expressing, Western Blot, Two Tailed Test